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b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<title>Multi-Processing Modules (MPMs) - Apache HTTP Server</title>
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b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p>
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b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.3</a></div><div id="page-content"><div id="preamble"><h1>Multi-Processing Modules (MPMs)</h1>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<p><span>Available Languages: </span><a href="/de/mpm.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
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b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<p>This document describes what a Multi-Processing Module is and
b38846b15c8891c6dec44dcc4f96ca40721bf663rbbhow they are used by the Apache HTTP Server.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#introduction">Introduction</a></li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<li><img alt="" src="/images/down.gif" /> <a href="#defaults">MPM Defaults</a></li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<li><img alt="" src="/images/down.gif" /> <a href="#static">Building an MPM as a static module</a></li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<li><img alt="" src="/images/down.gif" /> <a href="#dynamic">Building an MPM as a DSO module</a></li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<h2><a name="introduction" id="introduction">Introduction</a></h2>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>The Apache HTTP Server is designed to be a powerful and
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb flexible web server that can work on a very wide variety of
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb platforms in a range of different environments. Different
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb platforms and different environments often require different
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb features, or may have different ways of implementing the same
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb feature most efficiently. Apache has always accommodated a wide
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb variety of environments through its modular design. This design
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb allows the webmaster to choose which features will be included
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb in the server by selecting which modules to load either at
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb compile-time or at run-time.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>Apache 2.0 extends this modular design to the most basic
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb functions of a web server. The server ships with a selection of
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb Multi-Processing Modules (MPMs) which are responsible for
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb binding to network ports on the machine, accepting requests,
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb and dispatching children to handle the requests.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>Extending the modular design to this level of the server
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb allows two important benefits:</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <li>Apache can more cleanly and efficiently support a wide
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb variety of operating systems. In particular, the Windows
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb version of Apache is now much more efficient, since
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <code class="module"><a href="/mod/mpm_winnt.html">mpm_winnt</a></code> can use native
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb networking features in place of the POSIX layer used in
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb Apache 1.3. This benefit also extends to other operating
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb systems that implement specialized MPMs.</li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <li>The server can be better customized for the needs of the
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb particular site. For example, sites that need a great deal of
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb scalability can choose to use a threaded MPM like
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <code class="module"><a href="/mod/worker.html">worker</a></code> or <code class="module"><a href="/mod/event.html">event</a></code>, while sites requiring
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb stability or compatibility with older software can use a
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <code class="module"><a href="/mod/prefork.html">prefork</a></code>.</li>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>At the user level, MPMs appear much like other Apache
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb modules. The main difference is that one and only one MPM must
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb be loaded into the server at any time. The list of available
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb MPMs appears on the <a href="mod/">module index page</a>.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<h2><a name="defaults" id="defaults">MPM Defaults</a></h2>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<p>The following table lists the default MPMs for various operating
b38846b15c8891c6dec44dcc4f96ca40721bf663rbbsystems. This will be the MPM selected if you do not make another
b38846b15c8891c6dec44dcc4f96ca40721bf663rbbchoice at compile-time.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<table class="bordered"><tr><td>Netware</td><td><code class="module"><a href="/mod/mpm_netware.html">mpm_netware</a></code></td></tr>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<tr class="odd"><td>OS/2</td><td><code class="module"><a href="/mod/mpmt_os2.html">mpmt_os2</a></code></td></tr>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<tr><td>Unix</td><td><code class="module"><a href="/mod/prefork.html">prefork</a></code>, <code class="module"><a href="/mod/worker.html">worker</a></code>, or
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <code class="module"><a href="/mod/event.html">event</a></code>, depending on platform capabilities</td></tr>
a2a0abd88b19e042a3eb2a9fa1702c25ad51303dwrowe<tr class="odd"><td>Windows</td><td><code class="module"><a href="/mod/mpm_winnt.html">mpm_winnt</a></code></td></tr>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<h2><a name="static" id="static">Building an MPM as a static module</a></h2>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>MPMs can be built as static modules on all platforms. A single MPM
b45c1c292ff1fa635004ae81fa691f8cb3cdda85rbb is chosen at build time and linked into the server. The server must
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb be rebuilt in order to change the MPM.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>To override the default MPM choice, use the
a2a0abd88b19e042a3eb2a9fa1702c25ad51303dwrowe <code class="program"><a href="/programs/configure.html">configure</a></code> script. <em>NAME</em> is the name of the
a2a0abd88b19e042a3eb2a9fa1702c25ad51303dwrowe desired MPM.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>Once the server has been compiled, it is possible to determine which MPM
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb was chosen by using <code>/httpd -l</code>. This command will list every
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb module that is compiled into the server, including the MPM.</p>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb<h2><a name="dynamic" id="dynamic">Building an MPM as a DSO module</a></h2>
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb <p>On Unix and similar platforms, MPMs can be built as DSO modules and
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb dynamically loaded into the server in the same manner as other DSO
c3e342e5b0b9fea6617ee16d2da02c3ef2108126dougm modules. Building MPMs as DSO modules allows the MPM to be changed by
b38846b15c8891c6dec44dcc4f96ca40721bf663rbb updating the <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code> directive
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe for the MPM instead of by rebuilding the server.</p>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe <p>This feature is enabled using the
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe <code>--enable-mpms-shared</code> option of the <code class="program"><a href="/programs/configure.html">configure</a></code>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe With argument <code><em>all</em></code>, all possible MPMs for the platform
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe will be installed. Alternately, a list of MPMs can be specified as the
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe argument.</p>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe <p>The default MPM, either selected automatically or specified with the
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe <code>--with-mpm</code> option of the <code class="program"><a href="/programs/configure.html">configure</a></code>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe script, will be loaded in the generated server configuration file. Edit the
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code> directive to select a
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe different MPM.</p>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<p><span>Available Languages: </span><a href="/de/mpm.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<a href="/en/mpm.html" title="English"> en </a> |
3e392a5afd51526de3cb15d57ee46d8cb160ae65gregames<a href="/es/mpm.html" hreflang="es" rel="alternate" title="Espa�ol"> es </a> |
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<a href="/fr/mpm.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> |
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<a href="/ja/mpm.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<a href="/ko/mpm.html" hreflang="ko" rel="alternate" title="Korean"> ko </a> |
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<a href="/tr/mpm.html" hreflang="tr" rel="alternate" title="T�rk�e"> tr </a></p>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<p class="apache">Copyright 2009 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
83a8dc5a596a8a1b9d14f063268287d123b9ed7ewrowe<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="/faq/">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p></div>